1. Field of the Invention
The present invention relates to an image processing system, processing method, and storage medium.
2. Description of the Related Art
A tomography apparatus using an OCT (Optical Coherence Tomography), which utilizes interference caused by low coherent light, is known. By capturing an image of a fundus by such tomography apparatus, the state of interior of retinal layers can be three-dimensionally observed.
Imaging by the tomography apparatus is receiving a lot of attention since it is a technique helpful to give more adequate diagnoses of diseases. As a mode of such OCT, for example, a TD-OCT (Time Domain OCT) as a combination of a broadband light source and Michelson interferometer is known. The TD-OCT measures interfering light with backscattered light of a signal arm by scanning a delay of a reference arm, thus obtaining depth resolution information.
However, it is difficult for the TD-OCT to obtain an image fast. For this reason, as a method of obtaining an image faster, an SD-OCT (Spectral Domain OCT) which obtains an interferogram by a spectroscope using a broadband light source is known. Also, an SS-OCT (Swept Source OCT) which measures spectral interference by a single-channel photodetector using a fast wavelength swept light source is known.
In this case, if a shape change of a retina can be measured in a tomographic image captured by each of these OCTs, a degree of progress of a disease such as glaucoma and a degree of recovery after treatment can be quantitatively diagnosed. In association with such technique, Japanese Patent Laid-Open No. 2008-073099 discloses a technique for detecting boundaries of respective layers of a retina from a tomographic image and measuring thicknesses of the layers based on the detection result using a computer, so as to quantitatively measure the shape change of the retina.
With the technique of Japanese Patent Laid-Open No. 2008-073099 described above, a tomographic image within a range designated on a two-dimensional image is obtained, and layer boundaries are detected to calculate layer thicknesses. However, three-dimensional shape analysis of retinal layers is not applied, and the shape analysis result is not effectively displayed.